The invention relates in particular to devices which comprise:
two rigid frames fixed respectively to two rigid structures to be joined together,
an annular impervious elastomer partition inserted between the two frames for providing axial compression resistance, the partition and frames forming a first tight deformable chamber,
a flexible and impervious membrane carried by one of the frames and forming therewith a second tight deformable chamber,
a restricted passage providing permanent communication between the two chambers,
and a liquid mass filling the two chambers and the restricted passage.
As is known in such devices, the application on one of the frames in the axial direction of oscillations of relatively large amplitude (generally greater than 0.5 mm) and of relatively low frequency (generally of the order of 5 to 30 Hz) drives liquid back and forth through the passage between the two chambers. The liquid mass resonates when the frequency of the oscillations reaches a critical value, which depends on the ratio between the length and the cross section of the restricted passage. Such resonance provides excellent damping of the above-mentioned oscillations.
In accordance with a further know embodiment, the flexible membrane is covered by a rigid protective cover which is locally apertured so that the volume disposed inside the cover, but outside the membrane, is vented to the open air.
The cover is mounted on a corresponding frame of the device by crimping which ensures the tight assembly of the membrane on the frame.
The two rigid frames forming the device must be mounted on the two rigid structures. This usually requires cumbersome centering and fixing operations involving threaded fittings which are formed, for example, by bolt-nut systems which pass through lugs projecting externally from the cover.
The invention relates more particularly to an embodiment where the rigid frame is fixed to the cover by means of a rigid arm provided on a main bearing or borne structure (such as the crankcase of an engine or the chassis of a vehicle).
With such known embodiments, fixation to the main body or borne structure is generally provided by a screwed fitting between the cover, or the rigid frame to which it is fixed, and one of the ends of the connecting arm and between the other end of the connecting arm and the main structure.